How fast is the hr of a patient who is in v-fib?

Zero. In ventricular fibrillation, the heart is not beating at all - there is an uncoordinated quivering of the heart muscle without any effective contraction. V-fib leads to irreversible death within a few minutes. Immediate treatment (with an aed, automated external defibrillator) can convert v-fib to a rhythm that allows the heart to beat and restores the circulation.